Apparatus for treating hide and leather pieces in tanneries

ABSTRACT

An apparatus for continuously treating hide, leather and pieces of similar material by subjecting the pieces to be treated to exposure to a liquid treating agent selected to effect at least one of a tanning, post-tanning, oiling, fat-liquoring, surface dyeing, through dyeing and impregnating treatment in which pieces to be treated are successively fed to and through a liquid treating agent containing a treatment zone while the movement of the pieces through the zone is so guided that all surfaces of the pieces are exposed to umimpeded contact with the liquid treating agent and just prior to leaving the treatment zone, the leading ends of the successive pieces are grasped by and fed through cooperating pressing rollers to squeeze out excess liquid therefrom as they are leaving the treatment zone. The pieces leaving one treatment zone can be fed to and through a succeeding treatment zone containing the same or a different liquid treating agent and the intensity of the treating action can be increased by heating and/or subjecting the liquid within the zone to ultrasonic excitation or vibration.

APPARATUS FOR TREATING HIDE AND LEATHER PIECES IN TANNERIES lnventorsz Holm Ruffer, Uerikon-stafa;

WilTyKem p in, Uetikon am See: August Kraus, Mannedorf. all of Switzerland [73] Assignee: Staub 84 C 0. AG, Man nedorf, Switzerland [22] Filed: July 19,1971

[21] Appl. No.: 163,661

Related U.S. Application Data [62] Division of Ser. No. 851,654, Aug. 20, 1969.

[30] Foreign Application Priority Data Aug. 26, 1968 Switzerland 12757/68 Oct. 31, 1968 Switzerland 16245/68 [52] U.S. C1. 69/32, 69/21 [51] Int. Cl Cl4c 15/00 [58] Field of Search 69/32, 30; 68/44, 68/22 R [56] References Cited UNITED STATES PATENTS 7 2,530,494 11/1950 Vigerust 68/44 X 2,724,254 11/1955 Zanger.... 68/44 X 241,571 5/1881 Upson..... 68/44 X 3,165,912 1/1965 Grossman 69/10 3,203,207 8/1965 Poncelet 68/44 2,360,379 10/1944 Vetorino t 69/30 50,998 11/1865 Adams.... 69/32 X 89,166 4/1869 Pinter .1 68/44 X 1 1 Oct. 2, 1973 478,499 7/1892 Burns ..69/32 3,085,421 4/1963 Bucek .1 159 42 FOREIGN PATENTS OR APPLICATIONS 150,968 12/1961 U.S.S R ..69/32 Primary ExaminerAlfred R. Guest A11orney-Werner W. Kleeman ABSTRACT An apparatus for continuously treating hide, leather and pieces of similar material by subjecting the pieces to be treated to exposure to a liquid treating agent selected to effect at least one of a tanning, post-tanning, oiling, fat-liquoring, surface dyeing, through dyeing and impregnating treatment in which pieces to be treated are successively fed to and through a liquid treating agent containing a treatment zone while the movement of the pieces through the zone is so guided that all surfaces of the pieces are exposed to umimpeded contact with the liquid treating agent and just prior to leaving the treatment zone, the leading ends of the successive pieces are grasped by and fed through cooperating pressing rollers to squeeze out excess liquid therefrom as they are leaving the treatment zone. The pieces leaving one treatment zone can be fed to and through a succeeding treatment zone containing the sameor a different liquid treating agent and the intensity of the treating action can be increased by heating and/or subjecting the liquid within the zone to ultrasonic excitation or vibration.

32 Claims, 9 Drawing Figures PATENTEDBBT 2W SHEET 2 BF 4 qlllhllllllvvv APPARATUS FOR TREATING HIDE AND LEATHER PIECES IN TANNERIIES CROSS-REFERENCE TO RELATED APPLICATION The present application is a divisional application of our co-pending, commonly assigned, US. application, Ser. No. 851,654, filed Aug. 20, 1969, and entitled METHOD AND APPARATUS FOR TREATING HIDE AND LEATHER PIECES IN TANNERIES."

BACKGROUND OF THE INVENTION The present invention relates to an improved apparatus for treating hide or leather pieces by moving such hide or leather pieces in one or several known liquids for tanning, post-tanning, oiling, fat-liquoring, surface dyeing or through dyeing and impregnating.

In treating hide or leather pieces in tanneries, one endeavours to subject the surface and the cross-section of the pieces as uniformly as possible tothe action of the treatment liquid so as to obtain good leather quality. For this purpose, the hide or leather pieces are placed into drums or barrels in which they are, for example, tanned, oiled, fat-liquored, dyed and/or impregnated During the work process these barrels rotate for several hours around an axis in order to uniformly expose the leather on all sides to the action of the treatment liquid. The movement of the pieces in these barrels, which are mostly constructed of wood, is facilitated or aided by many irregularities in the form of pegs, impact boards or spiral-shaped baffle plates. By means of these irregularities and also by means of the rather rough interior barrel walls, the leather, however, is frequently damaged in its grain and it receives a coarse pore configuration as the result of the long fulling action. For this reason, the hides are frequently bound first so that the finer side of the leather (grain side) faces inwardly and thus can be subjected to less damage. The chemicals used in the barrels for tanning, dyeing or impregnating purposes are dissolved in or diluted with a substantial quantity of hot or cold water so that the amount of the various chemicals used in relation to the quantity taken up by the leather is rather large and thus uneconomical. The individual treatment of individual hide or leather pieces in barrels, is therefore, uneconomical, in addition to the substantial expenditure in time.

The driving of the barrels or drums requires a substantial use of energy, and the substantial expenditure in manual labor required for feeding and emptying the barrels as well as for the preliminary binding of the hide or leather pieces are also very disadvantageous aspects. Therefore, one has already begun to use barrels equipped with control devices for opening and closing the barrels and for dosing the chemicals. Such control devices are very expensive, however, and they also will not obviate the drawbacks attending the discontinuous manner of operation.

After taking the hide or leather pieces out of the barrels, they must furthermore be de-watered (or squeezed out) and stretched out, or they must be subjected in very wet condition to an expensive drying process.

Furthermore, there are also known processes such as dyeing by spraying and pouring, in which the dye solution for treating the leather is sprayed on or poured on only one side of the piece being treated. The dye solution must be closed and distributed such that a uniformly thin dye coat is formed on the leather. These processes have the drawback that the obtainable depth of penetration and color fastness are knowingly low.

SUMMARY OF THE INVENTION Therefore the primary object of the instant invention is to provide an improved apparatus for the continuous, easily controllable treating of hide and leather pieces which may also be sensitive and soft, possess irregular shapes and have varying moisture content. This apparatus shall enable, by utilizing an intensively and rapidly acting treatment liquid, the obtainment of a good and uniform tanning or post-tanning or surfaceor through dyeing, respectively, of the hide or leather pieces with the least expenditure of materials, manual labor, power, heat and time. Moreover, the swelling of the hide or leather pieces which occurred during known treatment in a barrel as a result of the 'long fulling dura tion is prevented and thus the pore configuration shall be significantly refined.

This object can be effectively realized in that the hide or leather pieces to be treated are conveyed in guided movement through one or several zones in which they come into unfettered or unimpeded contact with the liquid on all sides, wherein the concentration and temperature of the liquid(s) is selected such that one achieves an intensive action upon the hide or leather pieces and wherein the hide or leather pieces, immediately upon leaving the one or each of the several liquid zones, respectively, are uniformly relieved of their wetness or excess liquid by pressing.

Consistent with the aforegoing object, another object is to provide an apparatus construction wherein the speed of the guided movement of the hide or leather pieces through the liquid can be selected in dependency upon the intensity of the action of the used liquid and/or the desired product quality and the properties, for example, the thickness of or the initial moisture content of the pieces to be treated.

In carrying out the invention one must be careful that the hide or leather pieces are immediately, during and after leaving the wet zone, relieved of the adhering liquid to such an extent that individual surface zones are.

not subjected for differing lengths of time to the treating liquid through formation of trickles, puddles or drops. For this purpose, the pressing pressure of the discharge or pressing rollers can be regulated advanta-' geously in dependency upon the changing leather quality, for example, the change in thickness of the leather pieces being treated. During the movement in the'wet' or immersal zone, it must also be prevented that individual surface portions or areas of the pieces leave the immersal zone for a brief time, coming into-contact with air, since this would also result in a variable period during which the liquid acts upon the various surface and edge portions of the pieces.

For carrying out the invention one can use conventional tanning solutions of known composition which may contain, in addition to a tanning, dyeing and/or im-- pregnating medium, water, a conventional solvent and suitable.

Another and more specific object of the invention is to provide an apparatus for carrying out the treatment which includes means defining a treatment zone or vat, a conveyor means terminating at one side or the inlet side, respectively, of said zone or vat, pressing rollers provided at the outlet side of said zone or vat and means provided in the zone or vat for guiding and moving the hide or leather pieces which have to be transported through the liquid from the inlet to the outlet side of the zone or vat and in which said means permits an unimpeded, all-sided contact of the treating liquid with the leather pieces being moved through the treatment zone.

For the purpose of guiding the pieces without impeding the contact of the liquid therewith, suitable conveying means are, for example, grid or screen type conveyor belts, conveyor belts with projections thereon or rollers equipped with discs or brushes. In this mode, the liquid-permeable belts and rollers guide the hide or leather pieces from above and below in such manner that the pieces are guided forcibly and cannot, for example, float up out of the liquid in the zone or vat and thus the moving pieces safely reach the gap between the pressing rollers. Further, the gap between the pressing rollers is such that it lies only slightly above the level of the liquid in the zone or vat.

BRIEF DESCRIPTION OF THE DRAWINGS Further and more specific objects and advantages of the invention will be more readily apparent from the following description when taken in connection with the accompanying drawings in which:

FIG. 1 is a view partly in elevation and partly in longitudinal cross section diagrammatically illustrating an apparatus utilizing conveyor belt or band means for transporting or conveying hide or leather pieces through a treatment zone or vat;

FIG. 2 is a similar view illustrating a modified form of apparatus utilizing roller means for guiding and transporting or conveying hide or leather pieces through a treatment zone or vat;

FIG. 3 is a fragmentary top plan view of one form of transporting or conveying roller means;

FIG. 3a is a cross sectional view taken along line 3a3a of FIG. 3;

FIG. 4 is a top plan view illustrating another form of transporting or conveying roller means;

FIG. 5 is a diagrammatic cross sectional view illustrating another embodiment of an apparatus for carrying out the process of this invention in which the hide or leather pieces are guided and conveyed vertically through the treatmeant zone or vat and into the gap between the pressing rollers;

FIG. 6 is a side elevational view of an entire apparatus arrangement operating according to the principle shown in FIG. I;

FIG. 7 is a top plan view of the apparatus shown in FIG. 6; and

FIG. 8 is an end elevational view of the arrangement shown in FIGS. 6 and 7 as viewed from the right.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In all embodiments of the invention, the feeding of the hide or leather pieces I to the treatment zone takes place via a conveyor belt 2 which receives the pieces either from an identical or similar treatment installation preceding the instant installation, or upon which the pieces to be treated are placed by hand. Through spaced vanes or plates which define guiding surfaces 3 and 4, the pieces are introduced into the path of conveying or transporting means located within the liquid treatment zone. In the installation according to FIG. I, the pieces are moved through the liquid located in a vat 7 on a lower grid-like perforated or screen or wire mesh conveyor belt 5 which cooperates with a similar upper loading or pressing belt 6. Guide means such as rollers 6' keep the upper belt taut during its movement. The conveyor belt or belts, respectively, must be con structed such that they guide the hide or leather pieces, but at the same time assure unimpeded admission of or contact of the liquid with the surfaces of the pieces. Therefore, instead of using grid-like conveyor belts, one could also use, for example, belts equipped with projecting pegs, lugs, pins or bristles. The upper loading belt 6 has the purpose of holding the pieces on conveyor belt 5 and prevents them from floating up or forming wrinkles in their surfaces.

A safe guidance of the pieces is also required in order to introduce them safely into the roller gap of the pressing rollers 8 and 9 provided at the end of the conveyor path and at the outlet side of the vat, respectively. The conveyor belts 5, 6 of which one or both are driven, and the pressing rollers 8,9 are regulated in their speed by continuous drive means so that they always operate at their optimum conveyor speed. The conveyor belt 5 is completely immersed in the liquid, only the lower run of belt 6 is immersed in the liquid, most of the surface of pressing roller 8 is immersed and none of the surface of pressing roller 9 is immersed, thus making it possible to forego or eliminate the need for complicated ceilings or top structures for the vat. Both pressing rollers 8 and 9 are superimposed, it being preferable that they be so disposed in relation to one another that a common plane passing through their axes is inclined forwardly from the vertical in the conveying direction. The liquid level 10 in vat 7 is kept permanently at the same level by a recirculating pump and an overflow, see FIGS. 6 to 8. The liquid level is disposed relative to the conveyor belts in such manner that the leather pieces lose contact with the belts when still immersed within the liquid and that they thereafter only emerge above the liquid level and reach the roller gap. The liquid is brought to the desired temperature'and maintained at said temperature by a heating unit 11 disposed in the vat, said heating unit serving at the same time as a displacement body. 7 1

The heating unit is constructed as a displacement body in order to be able to carry out the leather treatment utilizing as little liquid as possible. As a result, it is also possible to treat individual leather pieces economically. Outside of the installation, there is a thermostat, not shown, through which the desired temperature of the liquid is maintained. At the outlet side of the pressing rollers 8 and 9, there are provided strippers I2 and I3 which lift the hide or leather pieces off of the surface of the pressing rollers so that they can be removed from the treatment installation or can be delivered to a further conveyor belt. Vat 7 and all parts coming into contact with the treatment liquid are made of stainless steel or plastic. A uniform pressing pressure of rollers 8 and 9 can be obtained by spring pressure, pneumatically, hydraulically or by a weight load.

The installation according to FIG. 2 differs from that of FIG. 1 in that in this embodiment, the hide or leather pieces are guided through the treatment liquid' between lower and upper rollers 14 and 15 to pressing rollers 8 and 9. At the circumference of rollers 14 and 15, there are secured annular rings 16 or spirally arranged bands, brushes, pegs or pins 17. FIGS. 3 and 3a illustrate in partial view several of rollers 14 and 15 having spirally arranged elevations 17 provided on their circumference. In the center or mid portion of the rollers, the spiral lines formed by the elevations are interrupted at 17 and continue on the other side of this interruption with opposite pitch.

By virtue of this reversal of the pitch, the hide or leather pieces are stretched perpendicularlyto the direction of conveyance so that formation of wrinkles in the pieces being transported is prevented.

FIG. 4 also illustrates transport rollers 14 or 15, but in this form, they have at their circumference circular rings 16 inclined outwardly from the center of the path of transport. These circular rings can be continuous or they can be interrupted in the manner of a toothed gear. By virtue of their being oppositely inclined on both sides of the center of the path of movement, the formation of wrinkles in the hide or leather pieces is prevented. The transport rollers are driven by chains 18 and 19 trained over sprockets on the ends of the roller shafts and driven by a continuous drive means, not shown. If desired, the drive for the rollers can be a variable speed drive. The roll of the lower transport rollers 14 fulfills at the same time the task of displacement heating body 11 in FIG. 1. The heating of the liquid bath in the FIG. 2 form of the invention takes place by a thermostat-controlled heating unit in the inflow line of the liquid. At the end of the installation, the pieces are taken over by a conveyor means 20 which transports them, for example, to an after-arranged additional installation of the identical type in which there can be a further or additional treatment.

In the installation according to FIG. 5, there is likewise a conveyor means 2 on which the hide or leather pieces 1 are guided to the liquid treating zone or bath.

In this embodiment the vat 21 is delimited at its lower side by the two pressing rollers 22 and 23 and at its sides by side walls 24 which are flush with the pressing rollers. The level 10 of the liquid bath in this vat'is always maintained at the same height by a recirculating pump, not shown, which draws the liquid out of a heated container and feeds it to the vat, and by an overflow in a side wall 24 which communicates with the heated container. In order to secure the guidance of the pieces 1 through the liquid bath, there are provided deflecting grates or vanes 25 on both sides of the conveyor path within the liquid. At the lower side of the pressing rollers, the strippers 26 contact with the surface of the rollers in order to convey pieces which may possibly adhere to the rollers by deflecting same onto the lower conveyor means 27. The conveyor belts and pressing rollers are likewise driven via continuous drive means and the pressing pressure of the pressing or squeezing rollers is controlled pneumatically. The pressing rollers are coated with an elastic coating 28 of differing hardness so that the roller gap closes at the sides of the hide or leather pieces and that only insignificant quantities of liquid can pass through the press or roller gap, respectively. The completely hermetic sealing of this installation, however, is more expensive and ifthere are possible leakages, then dye liquid, for example, can reach the leather which has been pressed out already and may leave dye traces. For this reason, the dyeing action at the edges of the leather is somewhat stronger in this installation than at the remaining leather surface. Also, the length of the conveyor path within the liquid can be varied only slightly.

FIGS. 6 to 8 illustrate the components of a treating installation that operates in accordance with the princi ple disclosed with relation to FIG. 1. Thus frame means 29 and 30, respectively, support the infeed conveyor means 2 and the vat and its associated components. The two frames are mounted in succession so that it is easy to monitor the treatment operation. The vat 7 is supported by the frame 30 and within the vat is the lower conveying belt 5 which may be of grid-like structure, a screen or wire mesh belt. The upper and cooperating similar belt 6 likewise is supported within the vat. Transverse frame components 31 of the frame 30 support interconnected motor-continuous drive units 32,34 and 33,35, respectively. The motor drive unit 32,34 drive the infeed belt 2 and the conveying and guiding or holding belts 5 and 6. The other motor-drive unit 33,35 drives pressing rollers 8 and 9. The pressing action of the rollers 8 and 9 is effected by pressure cylinder-piston means 36 and 27 which apply pressure to rods 36, 37 that are in turn connected to the opposite ends of the axle or shaft of roller 9. Suitable guide means, not shown, permit movement of roller 9 toward and away from roller 8. Pressure within the pressure cylinder-piston means is provided from a source, not shown, through an infeed line that communicates with a pressure adjusting regulating valve 38. The pressure source which can be compressed air, is fed via compressed air conduit 39 to the pressure cylinder means 36,37 and a safety valve 40 is associated with the compressed air conduit 39. In the illustrated installation, the heating unit 11 is located within the vat and functions as'a displacement body so that the amount of treating liquid required is at a minimum. The heating unit is of the steam type and steam is fed to the heater via a steam feed conduit 41. The heat output is controlled by a thermostat 42 located in the steam feed conduit 41. The condensate leaves the heating unit 11 via the discharge conduit 43.

Alongside the frame 30 is a supply container 45 which contains the particular treating liquid being used. A motor operated pump 44 withdraws the treating liquid from the container 45 and feeds the same into the vat 7 by means of an inlet conduit 46. An overflow conduit 47 communicates with the container .45 and keeps the liquid level 10 at a constant level. The pump 44 thus can function as a recirculating pump for recirculating the treating liquid.

In some treatments, particularly those in which the treating liquid is subjected to a strong or high heat and which treating liquid contains normally readily volatile solvents, a drawoff or suction hood device 48 can be associated with the vat so that the solvent can be drawn off by a suction fan 49 and conveyed to a solvent recovery unit 50. In the recovery unit the volative solvent vapors are condensed and recovered.

Furthermore, in order to subject the treating liquid to oscillation or vibrations, when necessary, to increase the intensity of the effect or action of the treating liquid, one or more ultrasonic heads 51 are mounted be:

neath the vat 7. In another arrangement, mechanical vibrators 52 can be arranged within the vat, see FIG. 1. Due to the vibration or ultrasonic excitation of the liquid, the intensity of the action of the liquid on the pieces being treated is increased so that the residence time of the pieces in the vat can be reduced. In other words, by utilizing the ultrasonic heads or mechanical vibrators, the speed of the treatment is increased and more pieces can be handled and subjected to the desired treatment in a given period of time.

It is to be understood that the drawoff or suction hood device shown diagrammatically in FIG. 1 can be associated with any form of vat or container and likewise, the ultrasonic generator or the mechanical vibrator can be utilized with any type vat, trough or chamber constructed to carry out the teachings of this invention.

The installations of this invention permit the use of rapidly acting liquids and so obtain a good and. uniform quality of leather. By means of the immediately follow- 4 of pieces to be treated and an outlet side for the discharging of treated pieces, conveyor means terminating at the inlet side above the liquid level for feeding successive pieces into said vat, cooperating pressing roller means at said outlet side for squeezing excess liquid from said pieces, means within said vat for continuously unimpedingly moving the pieces being treated through the vat below the liquid level therein from the inlet to the outlet side in an immersed floating condition in said liquid treating agent, said means being constructed and arranged as to allow unimpeded access of the treating liquid to substantially ali sides of the pieces being treated and means for maintaining said pieces being treated in a floating condition by preventing the rise of said pieces to the liquid surface while said pieces are being moved from the vat inlet to outlet.

2. Apparatus for treating hide, leather and pieces of similar material by subjecting the pieces to be treated to exposure to a liquid treating agent selected to effect at least one of a tanning, post-tanning, oiling, fatliquoring, surface dyeing, through dyeing and impregnating treatment comprising means defining a liquid containing vat having an inlet side for the introduction of pieces to be treated and an outlet side for the discharge of treated pieces, conveyor means terminating pore configuration of the leather is preserved. By virtue of the low quantity of'liquid and rapidity of the treatment, the individual leather pieces can also be treated economically.

In contrast to the treatment of hides or leather in barrels and in dewatering presses, there is achieved a substantial savings in material, labor, mechanical drive energy and heating water for diluting the liquid. By virtue of the low quantity of liquid required, the waste disposal plant of the tannery is also subjected to less work. Furthermore, the inventive installations require only a relatively small space for setting them up and they can achieve the output of many heretofore customary barrels or drums. The most important advantage of the inventive process,'however, lies in the continuous manner of operation so that it is possible by means of arranging many and, if desired, different length inventive machines of low cost factors in succession to mechanize and automate the manufacture of leather.

Further, the belts 5 and 6 are constructed with interstices such as to allow unimpeded liquid contact with the pieces and the term foraminous used in the claims is intended to cover any type conveyor arrangement that fulfills this purpose. Thus foraminous is intended to mean a grid-like structure, a wire mesh, a screen, a link and loop structure, chain connected transverse rods or any similar arrangement.

While there is shown and described present preferred embodiments of the invention, it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied and practiced within the scope of the following claims. Accordingly,

What is claimed is:

1. Apparatus for treating hide, leather and pieces of similar material by subjecting the pieces to be treated to exposure to a liquid treating agent selected to effect at least one of a tanning, post-tanning, oiling, fatliquoring, surface dyeing, through dyeing and impregnating treatment comprising means defining a liquid containing vat having an inlet side for the introduction at the inlet side above the liquid level for feeding successive pieces into said vat, cooperating pressing roller means at said outlet side for squeezing excess liquid from said pieces, said pressing roller means being positioned with its longitudinal axis in an inclined plane, means within the vat for guiding and continuously unimpedingly moving the pieces to be treated below the liquid level substantially linearly and without appreciable deflection within the vat from the inlet side to said pressing roller means in an immersed floating condition in said liquid treating agent, said means being constructed and arranged as to allow unimpeded access of the treating liquid to substantially all sides of the pieces being treated and means for maintaining said pieces being treated in floating condition while preventing the rise of said pieces to the liquid surface while said pieces are being moved from said vat inlet to outlet.

3. Apparatus as claimed in claim 2 and said guiding and moving means comprising foraminous endless conveyor means including at least two cooperating, facing runs within the vat and below the liquid level therein and between which said pieces are moved.

4. Apparatus as claimed in claim 2 and said guiding and moving means comprising endless conveyor means including at least two cooperating facing runs below the liquid level within the vat and having projections thereon and between which runs said pieces being treated are moved.

5. Apparatus as claimed in claim 2 and said guiding and moving means comprising roller means arranged in upper and lower series of parallel rollers displaced below the liquid level within the vat, and between which upper and lower series of rollers, said pieces being treated are moved.

6. Apparatus as claimed in claim 5 and circular rings mounted on the circumference of said rollers and said rings extending at outward inclinations from the center-line of the direction of movement of said rollers.

7. Apparatus as claimed in claim 5 and spiral band means mounted of the circumference of said rollers and said bands having opposite pitch on opposite sides of the center of the length of said rollers.

8. Apparatus as claimed in claim and helical band means mounted of the circumference of said rollers and said bands having opposite pitch on opposite sides of the center of the length of said rollers.

9. Apparatus as claimed in claim 6 and the periphery of said rings being interrupted to define piece engaging projections.

10. Apparatus as claimed in claim 5 and projections extending outwardly of the periphery of said rollers.

11. Apparatus as claimed in claim 10 and said projections being arranged in two generally helical formations of opposite pitch on opposite sides of the centers of the length of said rollers.

12. Apparatus as claimed in claim 2 and said guiding and moving means comprising conveyor means including at least two facing cooperating runs within said vat below the liquid level therein and between which said pieces are moved, means for driving one of said runs, said other run engaging the pieces being moved and moving therewith.

13. Apparatus as claimed in claim 2 and said guiding and moving means comprising conveyor means including at least two facing cooperating runs within said vat below the liquid level therein and between which said pieces are moved and drive means for driving both said runs.

14. Apparatus as claimed in claim 13 and said drive means being a continuous drive means.

15. Apparatus as claimed in claim 13 and said drive means being an infinitely variable drive means.

16. Apparatus as claimed in claim 5 and a continous drive means for said rollers.

17. Apparatus as claimed in claim 5 and an infinitely variable drive means for said rollers.

18. Apparatus as claimed in claim 2 and the gap between said cooperating pressing roller means being located slightly above the level of liquid within said vat.

19. Apparatus as claimed in claim 2 and the common plane passing through the axes of said pressing roller means being inclined forwardly in the direction of movement of said pieces.

20. Apparatus as claimed in claim 2 and a temperature controllable heating means constructed and arranged as a displacement body disposed within said vat.

21. Apparatus as claimed in claim 2 and at least one of said pressing roller means having an elastic surface.

22. Apparatus as claimed in claim 2 and means for regulating the pressure applied by said pressing roller means.

23. Apparatus as claimed in claim 22 and said means for regulating the pressure applied by said pressing roller means being fluid operated.

24. Apparatus as claimed in claim 22 and said means for regulating the pressure applied by said pressing roller means including weights.

25. Apparatus as claimed in claim 22 and said means for regulating the pressure applied by said pressing roller means including springs.

26. Apparatus as claimed in claim 2 and stripping means operatively associated with said pressing roller means at the outlet side thereof for ensuring removal of said pieces.

27. Apparatus as claimed in claim 2 and said vat having an inlet for liquid treating agent and an overflow outlet.

28. Apparatus as claimed in claim 2 and a volatile vapor drawoff means operatively associated with said vat and a volatile recovery unit communicating with said drawoff means.

29. Apparatus as claimed in claim 2 wherein said means for maintaining said pieces in a floating condition comprises roller means at least partially removed from said treating liquid.

30. Apparatus as claimed in claim 29 wherein said means for maintaining said pieces in a floating condition comprises an endless belt carried by said roller means.

31. Apparatus as claimed in claim 29 wherein said roller means includes a plurality of aligned parallel rolls.

32. Apparatus as claimed in claim 1 wherein said conveyor means for feeding pieces into said vat is externally positioned adjacent said vat and terminating at the inlet side above the liquid level in said vat whereby said pieces enter said vat liquid by gravity. 

1. Apparatus for treating hide, leather and pieces of similar material by subjecting the pieces to be treated to exposure to a liquid treating agent selected to effect at least one of a tanning, post-tanning, oiling, fat-liquoring, surface dyeing, through dyeing and impregnating treatment comprising means defining a liquid containing vat having an inlet side for the introduction of pieces to be treated and an outlet side for the discharging of treated pieces, conveyor means terminating at the inlet side above the liquid level for feeding successive pieces into said vat, cooperating pressing roller means at said outlet side for squeezing excess liquid from said pieces, means within said vat for continuously unimpedingly moving the pieces being treated through the vat below the liquid level therein from the inlet to the outlet side in an immersed floating condition in said liquid treating agent, said means being constructed and arranged as to allow unimpeded access of the treating liquid to substantially all sides of the pieces being treated and means for maintaining said pieces being treated in a floating condition by preventing the rise of said pieces to the liquid surface while said pieces are being moved from the vat inlet to outlet.
 2. Apparatus for treating hide, leather and pieces of similar material by subjecting the pieces to be treated to exposure to a liquid treating agent selected to effect at least one of a tanning, post-tanning, oiling, fat-liquoring, surface dyeing, through dyeing and impregnating treatment comprising means defining a liquid containing vat having an inlet side for the introduction of pieces to be treated and an outlet side for the discharge of treated pieces, conveyor means terminating at the inlet side above the liquid level for feeding successive pieces into said vat, cooperating pressing roller means at said outlet side for squeezing excess liquid from said pieces, said pressing roller means being positioned with its longitudinal axis in an inclined plane, means within tHe vat for guiding and continuously unimpedingly moving the pieces to be treated below the liquid level substantially linearly and without appreciable deflection within the vat from the inlet side to said pressing roller means in an immersed floating condition in said liquid treating agent, said means being constructed and arranged as to allow unimpeded access of the treating liquid to substantially all sides of the pieces being treated and means for maintaining said pieces being treated in floating condition while preventing the rise of said pieces to the liquid surface while said pieces are being moved from said vat inlet to outlet.
 3. Apparatus as claimed in claim 2 and said guiding and moving means comprising foraminous endless conveyor means including at least two cooperating, facing runs within the vat and below the liquid level therein and between which said pieces are moved.
 4. Apparatus as claimed in claim 2 and said guiding and moving means comprising endless conveyor means including at least two cooperating facing runs below the liquid level within the vat and having projections thereon and between which runs said pieces being treated are moved.
 5. Apparatus as claimed in claim 2 and said guiding and moving means comprising roller means arranged in upper and lower series of parallel rollers displaced below the liquid level within the vat, and between which upper and lower series of rollers, said pieces being treated are moved.
 6. Apparatus as claimed in claim 5 and circular rings mounted on the circumference of said rollers and said rings extending at outward inclinations from the center-line of the direction of movement of said rollers.
 7. Apparatus as claimed in claim 5 and spiral band means mounted of the circumference of said rollers and said bands having opposite pitch on opposite sides of the center of the length of said rollers.
 8. Apparatus as claimed in claim 5 and helical band means mounted of the circumference of said rollers and said bands having opposite pitch on opposite sides of the center of the length of said rollers.
 9. Apparatus as claimed in claim 6 and the periphery of said rings being interrupted to define piece engaging projections.
 10. Apparatus as claimed in claim 5 and projections extending outwardly of the periphery of said rollers.
 11. Apparatus as claimed in claim 10 and said projections being arranged in two generally helical formations of opposite pitch on opposite sides of the centers of the length of said rollers.
 12. Apparatus as claimed in claim 2 and said guiding and moving means comprising conveyor means including at least two facing cooperating runs within said vat below the liquid level therein and between which said pieces are moved, means for driving one of said runs, said other run engaging the pieces being moved and moving therewith.
 13. Apparatus as claimed in claim 2 and said guiding and moving means comprising conveyor means including at least two facing cooperating runs within said vat below the liquid level therein and between which said pieces are moved and drive means for driving both said runs.
 14. Apparatus as claimed in claim 13 and said drive means being a continuous drive means.
 15. Apparatus as claimed in claim 13 and said drive means being an infinitely variable drive means.
 16. Apparatus as claimed in claim 5 and a continous drive means for said rollers.
 17. Apparatus as claimed in claim 5 and an infinitely variable drive means for said rollers.
 18. Apparatus as claimed in claim 2 and the gap between said cooperating pressing roller means being located slightly above the level of liquid within said vat.
 19. Apparatus as claimed in claim 2 and the common plane passing through the axes of said pressing roller means being inclined forwardly in the direction of movement of said pieces.
 20. Apparatus as claimed in claim 2 and a temperature controllable heating means constructed and arranged as a displacement body disposed within said vat.
 21. ApparaTus as claimed in claim 2 and at least one of said pressing roller means having an elastic surface.
 22. Apparatus as claimed in claim 2 and means for regulating the pressure applied by said pressing roller means.
 23. Apparatus as claimed in claim 22 and said means for regulating the pressure applied by said pressing roller means being fluid operated.
 24. Apparatus as claimed in claim 22 and said means for regulating the pressure applied by said pressing roller means including weights.
 25. Apparatus as claimed in claim 22 and said means for regulating the pressure applied by said pressing roller means including springs.
 26. Apparatus as claimed in claim 2 and stripping means operatively associated with said pressing roller means at the outlet side thereof for ensuring removal of said pieces.
 27. Apparatus as claimed in claim 2 and said vat having an inlet for liquid treating agent and an overflow outlet.
 28. Apparatus as claimed in claim 2 and a volatile vapor drawoff means operatively associated with said vat and a volatile recovery unit communicating with said drawoff means.
 29. Apparatus as claimed in claim 2 wherein said means for maintaining said pieces in a floating condition comprises roller means at least partially removed from said treating liquid.
 30. Apparatus as claimed in claim 29 wherein said means for maintaining said pieces in a floating condition comprises an endless belt carried by said roller means.
 31. Apparatus as claimed in claim 29 wherein said roller means includes a plurality of aligned parallel rolls.
 32. Apparatus as claimed in claim 1 wherein said conveyor means for feeding pieces into said vat is externally positioned adjacent said vat and terminating at the inlet side above the liquid level in said vat whereby said pieces enter said vat liquid by gravity. 